Recent advances in the cell engineering have enabled culturing of various animal cells, including human cells. Research on the reconstruction of human tissues or organs using such cells, that is, what we call regenerative medicine, has progressed rapidly. Specifically, research has been conducted on, for example, regenerative medicine for regeneration of tissues and organs such as cartilages, bones, skin, or blood vessels.
The point of regenerative medicine is whether cells can grow and differentiate to form a three-dimensional, living tissue-like structure. In an exemplary method, a substrate is implanted into the patient's body so that cells from the surrounding tissue or organ can penetrate into the substrate and grow and differentiate to regenerate tissue or an organ.
Endoscopic resection of foci in living tissue is often conducted using an automatic suturing device or the like. The resection of delicate tissue (e.g., the lung, bronchus, liver, or alimentary canal) or tissue weakened by lesions may cause tearing of the tissue if the resection wound is merely sutured. Surgery of the lung, for example, may cause air leakage. To avoid these risks, a suture reinforcing material is often sutured to the resection site of the living tissue.
Nonwoven fabrics made of bioabsorbable materials, such as that disclosed in Patent Literature 1, have been proposed as the substrates for regenerative medicine or the suture reinforcing materials. When a nonwoven fabric made of a bioabsorbable material is used as the substrate for regenerative medicine or the suture reinforcing material, the nonwoven fabric is expected to allow cells to penetrate and grow in the voids in the fabric, enabling rapid tissue regeneration. When such a nonwoven fabric is used as the reinforcing material for delicate tissue, it can prevent tearing of tissue and thus prevent air leakage or the like. The nonwoven fabrics also have the excellent feature that they eliminate the need for surgical removal because they are decomposed and absorbed in the living body after a certain period of time.
In actual, however, the nonwoven fabrics made of conventional bioabsorbable materials sometimes do not accelerate tissue regeneration as much as expected.